The present invention relates to a method and apparatus for analyzing an NC program in NC machining, and more particularly, to an improved method and apparatus for analyzing an NC program in NC machining for performing a variety of machining controls using numerical control information, by which it is possible to abstract various machining information or machining conditions from an NC program used for actual machining and to store them as general purpose information which is expansively usable for a numerically controlled machine tool or another type of a numerically controlled machine tool.
A numerically controlled machine tool, in which an action of the machine tool can be automatically controlled by an NC program input, has been extensively utilized in various industrial fields as a computer numerically controlled machine tool (CNC machine tool) by being combined with micro processor techniques, power electronics techniques, or software techniques in recent years.
Numerical control information such as an NC program typically includes unique information such as a tool indexing command, a spindle rotational speed command, a feeding speed command, a moving and interpolation command, or an auxiliary function command, and a machining history. Numerical control information, which is necessary for machining to be tool controlled, is formed as an NC program for every machine tool.
In a prior art, numerical control information has been formed as a desired NC program using CAD/CAM or an automatic programming tool, under conditions where material data and a final parts shape are given, adjusted (i.e., corrected and edited) by repeatedly simulating or test-cutting with an actual machine tool at a machining site, and finally used for controlling machining of the tool as an actual machining NC program. Such a prior process for generating an NC program will now be described with reference to FIG. 1.
Material data and a final parts shape consisting of a work shape, drawing data, or the like are supplied to a process design section 1, where respective processes are determined on the basis of information with regard to a machine tool, and a jig or a holder read from a machine specification database 2, and a jig and a holder database 3. The term xe2x80x9cprocessxe2x80x9d means a group of all machining steps in which a workpiece never changes its fixed position. The term xe2x80x9cmachining stepxe2x80x9d means a group of work elements at the identical machining position of the workpiece. In other words, the term xe2x80x9cwork elementxe2x80x9d means a single machining or process performed by a tool, such as drilling or milling, and the term xe2x80x9cmachining stepxe2x80x9d means completing a single machining operation at the identical machining position of the workpiece by combining a plurality of work elements. For example, in screw hole cutting, a single machining step consists of three work elements; a center hole machining, a prepared hole machining, and a tapping machining.
After the above-described processes are determined at the process design section 1, in a work design section 4, machining steps to be performed at respective processes and work elements which are necessary for completing the machining steps are recognized on the basis of a work expansion database 5. A tool list and a work instruction sheet for respective work elements are next formed as shown by reference numerals 9 and 10 by using machining information from a tool database 6, a cutting condition database 7, and a machining time calculating database 8. Further, original numerical control information shown as a first process NC program, a second process NC program, etc. is outputted. There is a problem in that the original NC program formed should not mention that it is an optimal program. Therefore the original NC program is transmitted to an NC program correcting and editing section 11, at which a simulation, an idle operation, or a test cutting is performed on the basis of the output numerical control information so as to optimize a tool path and cutting conditions such as a cutting speed, a feeding speed, or a depth of cutting. It is necessary to incorporate know-how obtained at an actual machining site to optimize the program in addition to the above-mentioned simulating or test cutting method. However, in a prior art, since there is no database for doing such correcting work, it is done manually by a skilled worker in a usual case.
For example, in a case where chatter is generated at a part of a workpiece when numerical control information outputted from a CAM is test cut, the numerical control information is required to correct and alter a feeding speed or a rotation frequency of the part or to alter a width or a depth of cutting. Such correction is done by a skilled worker at a machining site in a prior art, and the original NC program is directly corrected at the NC program correcting and editing section 11.
Furthermore, when a tool path is also required to be delicately corrected, it is impossible to perform such feedback due to lack of CAM ability or the like in many cases. Even if the change of the databases is necessary; therefore, the know-how possessed by a machining site worker was rarely feedback to the databases to form an NC program.
Moreover, the reason for requiring the correction of an original NC program at a machining site in the prior art is that the original NC program for a unique workpiece is not always applied to a unique machine tool. Accordingly, the change of numerical control information may be required depending on ability or specification of a machine tool, which in turn needs to calculate a machining time again and to alter respective work instruction sheets.
After such optimization is done, the tool list and the work instruction sheet are formed again, and sent to a numerical control section 14 as a corrected first process tool list and work instruction sheet 12 and a corrected second process tool list and work instruction sheet 13. Therefore, in the prior art, these corrected first process NC program, second process NC program, etc. are used as actual machining NC programs at an actual machining site.
As described above, in the conventional NC machining system, there are problems such that work for correcting and editing numerical control information is not repeatedly utilized, feedback, or stored so as to be reusable as know-how. There is a large problem that it is difficult to reuse the program correcting and editing data such as various know-how at a machining site because the correction of the data is totally dependent on a skilled worker in the prior art as mentioned above. This means that an original NC program, which can be easily formed using a CAD/CAM system or an automatic programming system, can not be directly applied to each individual machine tool in the prior art; and therefore the editing and correction of the program are required for every machining process. An actual machining NC program, which is usable at a machining site, as a machining program for quantity production, can be obtained after such complicated processes have been completed. Accordingly, it does not sufficiently satisfy a machine tool user from the viewpoint of simple and easy use.
In addition, it is, of course, necessary to correct an NC program drastically when the type of machine tool is changed. Furthermore, such situations arise that an NC program formed in the past can not be utilized when a new machine tool of different type or an identical type with an improved specification is introduced.
In view of the foregoing problems, the object of the present invention is to analyze an actual machining NC program which has been corrected and edited, to extract various machining conditions such as know-how obtained at a machining site from an actual machining NC program actually used at the machining site for quantity production or an optimal machining information or machining conditions for a unique workpiece, and to allow them to be used as databases. The abstracted machining information or machining conditions will retrieve an optimal machining method or an optimal machining condition, which is inherent in respective machines, by being systematically associated with material information, drawing information, machine information, tool information or measured data, etc., which in turn allows an optimal machining program for respective machining sites and respective cases to be automatically and instantaneously programmed from the feedback databases. The databases can be supplied not only to one machine tool but also another machine tool. Therefore, it will be possible to perform all or the major part of correction and editing in accordance with a dialogue with the databases without depending on a skilled worker by opening the databases to all machine tools constituting a CIM (Computer Integrated Manufacturing) facility.
The present invention is an apparatus for analyzing an NC program in NC machining, wherein the NC machining is controlled by the NC program, comprising: machining method analyzing means for abstracting machining information or a machining condition by analyzing the NC program; and storage means for storing the machining condition rewritably.
The present invention is an apparatus for analyzing an NC program in NC machining, wherein the NC machining is controlled by the NC program, comprising: machining method analyzing means for abstracting machining information or a machining condition for each work element machining by analyzing the NC program; and storage means for storing the machining condition rewritably so as to correspond to each work element machining.
The present invention is an NC machining apparatus for performing NC machining controlled by an NC program comprising:
machining method analyzing means, to which an actual machining NC program, material data and a tool list are inputted, for abstracting machining information or a machining condition for each work element machining by analyzing the actual machining NC program; database forming means for converting the machining information or the machining condition abstracted for each work element machining into a database which is necessary to form the NC program; and an NC program forming database for storing the machining condition rewritably so as to correspond to each work element machining.
Furthermore, the present invention is an apparatus for analyzing an NC program in NC machining, according to claim 1, 2, or 3, wherein said machining method analyzing means comprising: a dividing section for dividing an actual machining NC program into respective work element machinings; and a machining condition abstracting section for abstracting a machining condition from the actual machining NC program.
In addition, the present invention is an apparatus for analyzing an NC program in an NC machining, according to claim 4, wherein a pattern definition storing section for collating and judging the work element machining from a tool machining locus is connected to the dividing section for dividing the actual machining NC program into respective work element machinings.
Moreover, the present invention is an NC machining apparatus for reforming NC machining according to claim 3, wherein the database contains at least a cutting condition database and a tool database.
In another aspect, the present invention is a method for analyzing an NC program in NC machining, wherein the NC machining is controlled by the NC program, comprising: a machining method analyzing step for abstracting machining information or a machining condition by analyzing the NC program; and a storage step for storing the machining condition rewritably.
Furthermore, the present invention is a method for performing NC machining controlled by an NC program comprising: a machining method analyzing step for abstracting machining information or a machining condition for each work element machining by analyzing the NC program; and a storage step for storing the machining condition rewritably so as to correspond to each work element machining.
Moreover, the present invention is a method for performing NC machining controlled by an NC program comprising: a machining method analyzing step, at which an actual machining NC program, material data and a tool list are inputted, for abstracting machining information or a machining condition for each work element machining by analyzing the actual machining NC program; and a database forming step for storing the machining information on the machining condition abstracted for each work element machining rewritably so as to correspond to each work element machining as a database which is necessary to form the NC program.
In another aspect, the present invention is a computer program product, which is executed by a computer, comprising a recording medium having a set of computer program instructions recorded thereon, the computer program product comprising: machining method analyzing means, recorded on the recording medium, for abstracting machining information or a machining condition by analyzing an NC program; and storage means, recorded on the recording medium, for storing the machining condition rewritably.